PROTOSOLAR CARBON ISOTOPIC COMPOSITION: IMPLICATIONS FOR THE ORIGIN OF METEORITIC ORGANICS

Ko Hashizume (1) , Marc Chaussidon (2) , Bernard Marty (2) , Kentaro Terada (3)

1 Osaka University [Osaka]
2 CRPG - Centre de Recherches Pétrographiques et Géochimiques
3 Hiroshima University

New ion probe isotopic measurements of carbon trapped within the 50 nm thick surface layer of lunar regolith grains strongly suggest that solar wind C is depleted in 13 C by at least 10% relative to terrestrial C. In order to account for the general 13 C enrichment of planetary C relative to solar C, we propose that the main carriers of C in these objects, i.e., organics, were formed in an environment that allowed a strong isotopic enrichment of 13 C in the solid phase. Such an environment is most likely a dense and warm circumstellar or interstellar gas medium, which could well correspond to the nebula surrounding the proto-Sun, where isotopic fractionation could be triggered by photochemical reactions.

Domaines: Astrophysique stellaire et solaire [astro-ph.SR]

Ko Hashizume, Marc Chaussidon, Bernard Marty, Kentaro Terada. PROTOSOLAR CARBON ISOTOPIC COMPOSITION: IMPLICATIONS FOR THE ORIGIN OF METEORITIC ORGANICS. The Astrophysical Journal, 2003, 600, pp.480-484. ⟨insu-01882002⟩